Visual Studio Code – Why has VS Code stopped discovering my python tests?

I’m using

• VS Code Version: 1.96.2
• Python 3.11.8
• MacOS Sonoma 14.5

I have a project that’s been working for a long time, but now VS Code is failing to discover/run my tests. When I go into the TESTING tab, I have a progress indicator that keep running forever and the test output is showing 0/0 tests run. It looks like it’s stuck in test discovery. Clicking the refresh button doesn’t help; I just get:

2025-01-04 23:02:05.066 [info] Running discovery for pytest using the new test adapter.
2025-01-04 23:02:05.066 [error] Test discovery already in progress, not starting a new one.

in the output tab. There are no problems listed in the problems tab. If I got into the terminal window and run the tests manually, all is good:

(.venv) roysmith@Roys-Mac-Mini dyk-tools % pytest
============================================================================== test session starts ===============================================================================
platform darwin -- Python 3.11.8, pytest-8.3.3, pluggy-1.5.0
rootdir: /Users/roysmith/dev/dyk-tools
plugins: socket-0.7.0, mock-3.14.0
collected 150 items                                                                                                                                                              

src/tests/bot/test_dykbot.py ..............                                                                                                                                [  9%]
src/tests/db/test_models.py ...                                                                                                                                            [ 11%]
src/tests/test___init__.py .                                                                                                                                               [ 12%]
src/tests/test_conftest.py .                                                                                                                                               [ 12%]
src/tests/web/test_core.py ......                                                                                                                                          [ 16%]
src/tests/web/test_data.py ......                                                                                                                                          [ 20%]
src/tests/wiki/test_article.py ........................                                                                                                                    [ 36%]
src/tests/wiki/test_hook.py .............................                                                                                                                  [ 56%]
src/tests/wiki/test_hook_set.py .........                                                                                                                                  [ 62%]
src/tests/wiki/test_nomination.py ............x......................                                                                                                      [ 85%]
src/tests/wiki/test_nomination_list.py ......................                                                                                                              [100%]

========================================================================= 149 passed, 1 xfailed in 4.15s =========================================================================

The only thing I can think of is that I’ve been refactoring my .zsh startup files so perhaps I messed up something in my environment, but given that the tests run manually, that seems unlikely. Any ideas what I might have broken?